Tired Brains = Sloppy Workouts?

The NY Times does a nice job reporting on a recent study suggesting that people who are mentally exhausted have a tougher time slogging through a serious workout.

Researchers were able to show that mentally effortful work reduced subjects’ capacity for subsequent workouts. Through an interesting trick in the study, they were also able to determine that the degradation in the physical workouts wasn’t due to physical exhaustion. That is, the flesh was willing, but the mind was beat.

How might this happen? One common resource used for both mental and physical workouts is willpower — the capacity that we each use to keep engaging in activities despite our urge to call it quits.

Willpower (also known as executive function) is one of the most important resources at our disposal when it comes to good behavior. It allows us to do things that are unpleasant in the here and now, but serve us well in the future.

But willpower is now known to be a limited resource, which means that it can be depleted. That means that if we burn it up on one effortful activity (e.g., mentally challenging work), we won’t have much of it left for subsequent effortful activities.